Changes in endogenous levels of IAA and PAA in rice seed during development, prediction of auxin signaling proteins and docking for its binding efficiency with auxin molecules

Indole-3-acetic acid (IAA) and phenyl acetic acid (PAA) are two major physiologically active auxins, found in higher plants. The objective of this study was to evaluate changes in the endogenous levels of IAA and PAA in rice (Oryza sativa) seed and predict probable transporter and efflux (signaling) proteins for docking with auxins from the available rice genome data. IAA and PAA were estimated during rice seed development using sensitive and specific antibodies against each hormone. The levels of IAA and PAA were higher when sink size development was at its peak, suggesting an important role played by the auxin in sink size development of rice seed. Furthermore, auxin binding transporters proteins of rice were confirmed for docking purpose and compared with Arabidopsis and maize proteins. In this context, PAA docked with known IAA proteins; although, docking score of IAA was higher than that of PAA in rice seed. Twelve genes of the auxin efflux carrier (PIN family) of rice were also analysed for phylogeny relatedness with Arabidopsis and maize, to further understanding auxin concentrations and efflux within rice seeds. The predicted PIN proteins for IAA efflux of rice showed docking affinities with PAA, revealed its role in maintaining physiological concentrations of auxins in rice seeds

Changes in endogenous levels of IAA and PAA in rice seed during development, prediction of auxin signaling proteins and docking for its binding efficiency with auxin molecules

Indole-3-acetic acid (IAA) and phenyl acetic acid (PAA) are two major physiologically active auxins, found in higher plants. The objective of this study was to evaluate changes in the endogenous levels of IAA and PAA in rice ( Oryza sativa ) seed and predict probable transporter and efflux (signaling) proteins for docking with auxins from the available rice genome data. IAA and PAA were estimated during rice seed development using sensitive and specific antibodies against each hormone. The levels of IAA and PAA were higher when sink size development was at its peak, suggesting an important role played by the auxin in sink size development of rice seed. Furthermore, auxin binding transporters proteins of rice were confirmed for docking purpose and compared with Arabidopsis and maize proteins. In this context, PAA docked with known IAA proteins; although, docking score of IAA was higher than that of PAA in rice seed. Twelve genes of the auxin efflux carrier (PIN family) of rice were also analysed for phylogeny relatedness with Arabidopsis and maize, to further understanding auxin concentrations and efflux within rice seeds. The predicted PIN proteins for IAA efflux of rice showed docking affinities with PAA, revealed its role in maintaining physiological concentrations of auxins in rice seeds.L\u2019acide indole-3-ac\ue9tique (IAA, Indole-3-acetic acid) et l\u2019acide ph\ue9nylac\ue9tique (PAA, phenyl acetic acid) sont deux auxines physiologiquement actives majeures, trouv\ue9es dans les plantes sup\ue9rieures. L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9valuer les changements dans les niveaux endog\ue8nes d\u2019IAA et de PAA dans les graines de riz (Oryza sativa) et de pr\ue9dire les prot\ue9ines de transport et d\u2019efflux (signalisation) probables pour l\u2019amarrage aux auxines \ue0 partir des donn\ue9es disponibles sur le g\ue9nome du riz. L\u2019IAA et le PAA ont \ue9t\ue9 estim\ue9s au cours du d\ue9veloppement des semences de riz en utilisant des anticorps sensibles et sp\ue9cifiques contre chaque hormone. Les niveaux d\u2019IAA et de PAA \ue9taient plus \ue9lev\ue9s lorsque le d\ue9veloppement de la taille du puits \ue9tait \ue0 son maximum, sugg\ue9rant un r\uf4le important jou\ue9 par l\u2019auxine dans le d\ue9veloppement de la taille du puits des graines de riz. De plus, les prot\ue9ines transporteuses de liaison aux auxines du riz ont \ue9t\ue9 confirm\ue9es \ue0 des fins d\u2019amarrage et compar\ue9es aux prot\ue9ines d\u2019Arabidopsis et de ma\uefs. Dans ce contexte, le PAA s\u2019est amarr\ue9 \ue0 des prot\ue9ines IAA connues ; cependant, le but d\u2019amarrage de l\u2019IAA \ue9tait plus \ue9lev\ue9 que celui du PAA dans les semences de riz. Douze g\ue8nes du transporteur d\u2019efflux d\u2019auxine (famille PIN) du riz ont \ue9galement \ue9t\ue9 analys\ue9s pour la phylog\ue9nie avec Arabidopsis et le ma\uefs, afin de mieux comprendre les concentrations d\u2019auxine et l\u2019efflux dans les graines de riz. Les prot\ue9ines PIN pr\ue9dites pour l\u2019efflux d\u2019IAA du riz ont montr\ue9 des affinit\ue9s d\u2019amarrage avec le PAA, ont r\ue9v\ue9l\ue9 son r\uf4le dans le maintien des concentrations physiologiques d\u2019auxines dans les graines de riz

Physiological and biochemical changes associated with sink development in cotton seeds. I. Glycosidases and water content.

Three cotton genotypes (Gossypium hirsutum L. H-4, H-6, G. herbaceum V797) varying in their final seed weight were analyzed for the growth and glycosidases activity. Five glycosidases, viz., a-b-galactosidases, a-b-glucosidases and a-mannosidases were estimated in cytoplasmic and wall-bound fractions. Data on dry weight and water content were fitted to polynomial equations and third degree polynomial equation was best-fit. Rate of dry matter accumulation showed closed relationship with water content in all three genotypes. The values for correlation coefficient {r= 0.956(H-4), r= 0.892(H-6) and r= 0.983 (V797)}, were statistically significant. No correlation between ionically wall-bound glycosidases and sink development was observed. In cytoplasmic fraction, the activities were higher during latter phase of dry matter accumulation. Probable role of these enzymes in mobilization of storage products during seed development is discussed

Turnover of cell wall components during sink development in seeds of three cotton genotypes

Size of the cells in developing seed is one of the major factors that regulate yield potentials. Seed of three cotton genotypes, Gossypium hirsutum. L cv (H-4; H-8) G. herbaceum L. cv (G. Cot-15) exhibits variation in their final seed size (large, middle and smaller) were studied for growth and changes in cell wall components during entire period of seed development. High and low molecular weight xyloglucan contents were extracted with 1M and 4M alkali, respectively. Initially the high and low molecular weight xyloglucan contents remained low and increased when cell size stabilized. Changes in esterified and non-esterified pectic substances were also fractionated from the cell wall of developing seed and theirs role in cell elongation phase is discussed. It was observed that bigger seed has higher xyloglucan contents than that of middle and smaller sized seed. Pectic substances were higher during elongation phase in all genotypes. The role of these polysaccharides in sink size development is discussed

Influence of flowering time and fruiting pattern on yield components of three cotton genotypes.

Cotton genotypes H-6, H-4 (Gossypium hirsutum L.) and V797 (Gossypium herbaceum L.) were analyzed for fruiting pattern (i.e. distribution of flowers, numbers of bolls and its dry weight on different branches) and percent (%) dry matter partitioning into the different components of the boll (seed, fiber and boll wall). Percent distribution of flowers, bolls and dry weight within the plant varied distinctly among the genotypes studied. In higher yielding genotypes (H-4 and H-6), during the initial stage of plant growth for about 10 days, 60-80% of dry matter was partitioned into boll wall and decreased up to 12-15% as the boll developed (nearly 45 days). Contrary to this, seed and fiber accumulated dry matter during development (60-75%). Abscission rate increased with an increase in boll load in all three genotypes and it was significantly higher in the lower yielding variety, V797. A reduction in boll and seed number, seed and fiber dry weight was observed with the progress in the season and was significantly higher in V797 as compared to H-4 and H-6