Anish Malladi

University of Georgia | UGA · Department of Horticulture

Fruit ripening is a highly coordinated process involving molecular and biochemical changes that collectively determine fruit quality. The underlying metabolic programs and their transitions leading to fruit ripening remain largely under-characterized in blueberry (Vaccinium sp.), which exhibits atypical climacteric behavior. In this study, we focus...

Aminoethoxyvinylglycine (AVG) is widely used in commercial apple ( Malus × domestica Borkh.) production to reduce preharvest fruit drop (PFD) and delay ripening for harvest management. Recently, the maximum allowable concentration of AVG was doubled (up to 264 mg⋅L ⁻¹ ). Reports of the relationship between the AVG concentration and fruit growth, si...

Apple ( Malus × domestica ) growers can incur significant economic losses when fruit drop before they can be harvested [preharvest fruit drop (PFD)]. In some years and cultivars, more than 30% of potential yield can be lost. Growers frequently apply plant bioregulators to reduce PFD, either via delay in maturity [aminoethoxyvinylglycine (AVG), 1-me...

Early fruit growth in peach is characterized by cell production. Cytokinins have established roles in regulating cell division and may regulate cell production during early fruit growth. However, the role of active cytokinins and regulation of their metabolism are not well characterized in the peach fruit. In this study, fruit growth parameters, co...

To investigate K absorption and transport mechanisms by which pear rootstock genotypes respond to low-K stress, seedlings of a potassium-efficient pear rootstock, Pyrus ussuriensis, and a potassium-sensitive rootstock, Pyrus betulifolia, were supplied with different K concentrations in solution culture. Significant differences in the absorption rat...

Climacteric fruits display an increase in respiration and ethylene production during the onset of ripening, while such changes are minimal in non-climacteric fruits. Ethylene is a primary regulator of ripening in climacteric fruits. The ripening behavior and role of ethylene in blueberry (Vaccinium sp.) ripening is controversial. This work aimed to...

Fruit size is a commercially valuable trait that is determined by the extent of fruit growth. In apple, (Malus × domestica Borkh.), early fruit growth is facilitated by intensive cell production, but mechanisms regulating these processes are not well understood. In this study, members of five gene families involved in growth regulation were identif...

Apple crop load management and related fruitlet abscission have been major research priorities for the last century in pomology. From these efforts, two main models were developed to explain the mechanisms leading to fruitlet abscission: correlatively driven abscission proposed by Bangerth; and carbohydrate stress initially proposed by Botton et al...

Sustaining the fourfold increase in blueberry (Vaccinium sp.) production witnessed during the previous two decades requires better understanding of its mineral nutrient physiology. The primary goals of this review are to evaluate our current understanding of the physiology of nitrogen (N) and calcium (Ca) nutrition in blueberry. Nitrogen concentrat...

Potassium (K) plays a crucial role in multiple physiological and developmental processes in plants. Its deficiency is a common abiotic stress that inhibits plant growth and reduces crop productivity. A better understanding of the mechanisms involved in plant responses to low K could help to improve the efficiency of K use in plants. However, such r...

The apple (Malus × domestica) fruit consists of two main fleshy tissues, cortex and pith, that are of diverse origins and contribute differentially to final fruit size. The contribution of these fruit spatial constituents to variation in fruit morphology has not been determined previously. We developed an image-analysis based method that uses two-d...

The efficacy of auxinic herbicides, a valuable weed control tool for growers worldwide, has been shown to vary with the time of day in which applications are made. However, little is known about the mechanisms causing this phenomenon. Investigating the differential in planta behavior of these herbicides across different times of application may gra...

Fruit size is a highly valued commercial trait in peach. Competition among fruit and among other sinks on a tree reduces potential growth rate of the fruit. Hence, crop-load management strategies such as thinning (removal of flowers or fruit) are often practiced by growers to optimize fruit size. Thinning can be performed at bloom or during early f...

Background: The major fleshy tissues of the apple fruit are spatially separable into cortex and pith. These tissues display differential growth during development. Key features of such differential growth, and sink metabolic programs supporting it have not been investigated previously. We hypothesized that differential growth between these fruit t...

Fruit growth and development are processes of primary biological importance and of considerable commercial significance. In apple, the fleshy fruit is derived largely from non‐ovarian tissue. Regulation of fruit growth in apple is therefore likely distinct from that in other model fleshy fruit species. Fruit growth is an integration of multiple pro...

Ripening in blueberry fruit is irregular and occurs over an extended period requiring multiple harvests, thereby increasing the cost of production. Several phytohormones contribute to the regulation of fruit ripening. Certain plant growth regulators (PGRs) can alter the content, perception, or action of these phytohormones, potentially accelerating...

Southern highbush blueberry (SHB; Vaccinium corymbosum L. interspecific hybrids) is highly susceptible to freeze damage in sub-tropical climates, but the process is poorly understood. To address the issue, freeze tolerance experiments were conducted on two common cultivars of SHB, Emerald and Farthing, during the winters of 2015-16 and 2016-17. Flo...

Blueberry (Vaccinium sp.) is thought to display a preference for the ammonium (NH4⁺) form over the nitrate (NO3⁻) form of inorganic nitrogen (N). This N-source preference has been associated with a generally low capacity to assimilate the NO3⁻ form of N, especially within the shoot tissues. Nitrate assimilation is mediated by nitrate reductase (NR)...

Drought stress reduces stem elongation and cell expansion. Since gibberellins (GAs) play an important role in controlling cell elongation, the objective of this study was to determine if the reduction in growth under drought stress is associated with altered GA metabolism or signaling. We exposed 'Moneymaker' tomato (Solanum lycopersicum) to drough...

Fruit detachment in blueberry (Vaccinium sp.) may occur through the physiological process of abscission or through physical separation by breakage. Natural and induced fruit detachment through abscission occurs at the peduncle pedicel junction (PPJ), while detachment through breakage typically occurs at the fruit pedicel junction (FPJ). The ease of...

Fruit abscission in blueberry (Vaccinium sp.) occurs at the pedicel/peduncle junction (PPJ). Growth regulators such as methyl jasmonate (MeJa) and ethephon accelerate the progression of abscission at this zone. It is not known whether the abscission zone at the PPJ is sufficient to perceive and respond to these growth regulator applications or if t...

Daily Water Use of Tomato Plants as Affected by Environmental Conditions and Plant Age Alex Litvin, Anish Malladi, and Marc van Iersel Daily water use (DWU) by plants is affected by the size of the plants as well as the environmental conditions to which they are exposed. As plants grow, DWU increases as well. Environmental conditions, such as d...

Fruit growth in apple (Malus ×domestica) is achieved through a combination of cell production and expansion, processes which are in-turn regulated by multiple genes. Cell production is regulated by the progression of individual cells through the cell cycle. Multiple cell cycle genes closely associated with the regulation of cell production during d...

Organ separation through abscission occurs at abscission zones (AZs) and involves the breakdown of cell walls. During abscission, the AZ cells respond to the various signals, and activate cell wall loosening enzymes. The spatial and temporal regulation of the dissolution of primary cell wall polysaccharides and middle lamella is not completely unde...

Carbohydrate availability is a key factor determining fruit growth in apple (Malus ·domestica) and other fruits. However, the molecular mechanisms regulating fleshy fruit growth in response to changes in carbohydrate availability are not well understood. In this study, carbohydrate availability was manipulated by reducing fruit load, and its effect...

A portable, handheld, mechanical shaking device was developed and its effects on fruit detachment in rabbiteye bluebbery (Vaccinium ashei Reade) and southern highbush blueberry (hybrids of mostly Vaccinium corymbosum L. and Vaccinium darrowi Camp.) were evaluated. The instrument facilitated effective detachment of fruit within a branch, especially...

A better understanding of fruit detachment and the processes mediating it is essential to improve the efficiency of mechanical harvesting in blueberry (Vaccinium sp.). In blueberry, fruit detachment may occur either at the point of attachment of the pedicel to the peduncle [peduncle-pedicel junction (PPJ)] or at the point of attachment of the pedic...

Two abscission agents, ethephon and methyl jasmonate, were investigated in five studies to determine their potential for increasing fruit detachment during harvest in rabbiteye (Vaccinium ashei Reade) and southern highbush (hybrids based largely on Vaccinium corymbosum L. and Vaccinium darrowi Camp.) blueberry. In the first study with a rabbiteye b...

Plant responses to drought stress vary depending on the severity of stress and the stage of drought progression. To improve the understanding of such responses, the leaf physiology, abscisic acid (ABA) concentration, and expression of genes associated with ABA metabolism and signalling were investigated in Petunia × hybrida. Plants were exposed to...

Shading during early fruit development reduces fruit growth and initiates fruit abscission in apple (Malus · domestica). The mechanisms mediating the decline in fruit growth in response to shading are not well understood. In this study, the effects of shading during early fruit development on cell production and expansion were investigated. Additio...

Abscission is a highly coordinated and regulated process which responds to developmental cues, and various biotic and abiotic stresses. Organ separation occurs at abscission zones (AZs) and involves the breakdown of cell walls. The spatial and temporal regulation of the dissolution of primary cell wall polysaccharides and middle lamella is not comp...

Fruit growth in apple (Malus × domestica Borkh.) is mediated by cell production and expansion. Genes involved in regulating these processes and thereby fruit growth, are not well characterized. We hypothesized that the apple homolog(s) of AINTEGUMENTA (ANT), an APETALA2-repeat containing transcription factor, regulates cell production during fruit...

Growth and gene expression during fruit development in ‘Gala’. The table displays data corresponding to Figure 2 for Fruit diameter (Figure 2A), Cell layers (Figure 2B), Relative cell production rate (RCPR; Figure 2C) and Cell area (Figure 2D). The table also displays expression data for MdANT1 and MdANT2 from Figure 3. Fruit diameter was not measu...

Growth and gene expression in thinned [A] and un-thinned fruit [B] of ‘Golden Delicious Smoothee’. The table shows data corresponding to Figure 4 for Fruit diameter (Figure 4A), Cell layers (Figure 4B), Relative cell production rate (RCPR; Figure 4C) and Cell area (Figure 4D). The table also shows expression data for MdANT1 and MdANT2 from Figure 5...

List of primer sequences used for sequencing MdANT1 and MdANT2.

List of primers used for analysis of ANTs, AILs, and MdMADS’ gene expression with qRT-PCR.

Comparison of the predicted amino acid sequences of plant ANTs. (A) Phylogenetic analysis of two apple ANTs, and Arabidopsis ANT and AILs was performed using the neighbor joining distance method of MUSCLE. Sequences for Arabidopsis ANT and AILs were retrieved from the NCBI database. The accession numbers for Arabidopsis AILs are: AtAIL1 (AT1G72570)...

Expression of the AIL genes during fruit development in ‘Gala’. The normalization factor was determined as the geometric mean of expression of MdGAPDH and MdACTIN. Fold change in expression is presented relative to expression during full bloom. Error bar represents the standard error of the mean of four biological replicates (n = 4).

Fruit growth and gene expression in ‘Gala’ [A] and ‘Golden Delicious Smoothee’ [B]. The table displays data corresponding to Figure 6 for Fruit diameter (Figure 6A), Cell layers (Figure 6B), Relative cell production rate (RCPR; Figure 6C) and Cell area (Figure 6D). Fruit diameter was not measured at 19 growing degree days (GDD) after full bloom in...

Expression of MdMADS5 and MdMADS10 in the core and the cortex tissues of ‘Gala’ apple during flower and early fruit development. Closed circles represent cortex tissues and open circles represent core tissues. Core and cortex tissues were separated using laser capture microdissection. Gene expression was determined using quantitative RT-PCR and was...

Drought stress commonly limits plant growth. To understand plant responses to different severities of drought stress, we investigated the leaf physiology, ABA concentration, and expression of genes associated with ABA metabolism and signaling in Petunia ×hybrida. Plants (Petunia ×hybrida ‘Apple Blossom’) were grown in a soilless substrate, which wa...

Blueberry is a rapidly emerging fruit crop. Progress in our understanding of blueberry physiology can be greatly enhanced through the application of transcriptomics tools. RNA of high yield and quality is an indispensable prerequisite for transcriptome analysis. However, isolation of RNA of high quality and yield in blueberry is difficult due to th...

Application of transcriptomics approaches can greatly enhance our understanding of blueberry physiology. The success of transcriptomics approaches is dependent on the extraction of high-quality RNA which is complicated by the abundance of polyphenolics and polysaccharides in blueberry. Additionally, transcriptomics requires the accurate quantificat...

Cell production is an essential facilitator of fruit growth and development. Cell production during carpel/floral-tube growth, fruit set, and fruit growth, and its regulation by cell cycle genes were investigated in apple (Malus×domestica Borkh.). Cell production was inhibited during late carpel/floral-tube development, resulting in growth arrest b...

Fruit size is a valuable commercial trait in blueberry. The cellular basis of variation in fruit size among rabbiteye blueberry (Vaccinium ashei) genotypes was investigated. Twenty genotypes, including cultivars and advanced selections from the University of Georgia blueberry breeding program, were analyzed. Among the 20 genotypes, fruit weight and...

Polyamines (PAs) are ubiquitous, polycationic biogenic amines that are implicated in many biological processes, including plant growth and development, but their precise roles remain to be determined. Most of the previous studies have involved three biogenic amines: putrescine (Put), spermidine (Spd) and spermine (Spm), and their derivatives. We ha...

Final fruit size in apple (Malus x domestica) is of great economic significance. Apple fruit development involves cell division during the first few weeks after bloom, followed by cell expansion. Final fruit size is greatly regulated by cell production which is in turn controlled by the activity of multiple genes. Several AP2-domain transcription f...

Fruit size is a valuable commercial trait in crops such as blueberry. In spite of its importance, little is known regarding the mechanisms involved in regulating fruit size. In this study, we investigated the basis of variation in fruit size across rabbiteye blueberry genotypes. Twenty rabbiteye blueberry cultivars and advanced selections from the...

Fruit size regulation was studied in the apple cultivar 'Gala' and a large fruit size spontaneous mutant of 'Gala', 'Grand Gala' (GG). GG fruits were 15% larger in diameter and 38% heavier than 'Gala' fruits, largely due to an increase in size of the fruit cortex. The mutation in GG altered growth prior to fruit set and during fruit development. Pr...

Unprecedented progress during the last three decades in our understanding of the principles of a living cell, particularly the identification of genes and signaling pathways involved in cell differentiation and organ development, has brought us a broader insight into plant biological processes. Technological advancements are revealing new and funda...

Fruit growth in apple is facilitated by the coordinated progression of cell production and cell expansion. Molecular mechanisms involved in the regulation of cell production during early fruit growth are not well understood. Core cell cycle genes control progression through the cell division cycle and may therefore regulate cell production during e...

Understanding leaf and fruit abscission is essential in order to develop strategies for controlling the process in fruit crops. Mechanisms involved in signalling leaf and fruit abscission upon induction by abscission agents were investigated in Citrus sinensis cv. ‘Valencia’. Previous studies have suggested a role for phospholipid signalling; hence...

Additional index words. apical dominance, epinasty, photoperiod, root anaerobiosis, soil moisture status, stomatal conductance, tuberization Abstract. Plant growth regulators (PGRs) play important roles in the way plants grow and develop. Myriad processes important to horticultural crops are regulated by PGRs. Changes in the presence, balance, and...

Fruit size is a commercially valuable trait in apple as well as in other fruit crops. These studies investigated the role of the cell division cycle in regulating fruit size of apple. Final cell number within the fruit cortical region was positively related to the fruit diameter (r2 = 0.90). The large fruit size cultivar 'Golden Delicious' differed...