Abstract
Sink/source relationships, regulating the mobilization of stored carbohydrates from the vegetative tissues to the grains, are of key importance for grain filling and grain yield. We used different inhibitors of plant hormone action to assess their effects on grain yield and on the expression of hormone-associated genes. Among the tested chemicals, 2-indol-3-yl-4-oxo-4-phenylbutanoic acid (PEO-IAA; antagonist of auxin receptor), nordihydroguaiaretic acid (NDGA; abscisic acid (ABA) biosynthesis inhibitor), and 2-aminoisobutyric acid (AIB; ethylene biosynthesis inhibitor) improved grain yield in a concentration dependent manner. These effects were also dependent on the plant developmental stage. NDGA and AIB treatments induced an increase in photosynthesis in flag leaves concomitant to the increments of starch content in flag leaves and grains. NDGA inhibited the expression of ABA-responsive gene, but did not significantly decrease ABA content. Instead, NDGA significantly decreased jasmonic acid and jasmonic acid-isoleucine. Our results support the notion that the specific inhibition of jasmonic acid and ethylene biosynthesis resulted in grain yield increase in rice.
Highlights
Rice is one of the most important food crops worldwide, and an increased interest in developing high grain-yielding cultivars have led to the development of new varieties using conventional breeding programs [1]
Plants treated at pre-anthesis with the highest and intermediate concentrations of all the hormone inhibitors tested, and the lowest concentrations of 2-aminoisobutyric acid (AIB), silver nitrate (AgNO3), and 2-indol-3-yl-4-oxo-4-phenylbutanoic acid (PEO-indole-3-acetic acid (IAA)), induced a reduction in shoot dry weight (SDW) and/or Grain Yield (GY) (Table 1)
When the hormone inhibitors were applied at both pre- and post-anthesis stages, they induced a decrease in SDW and/or GY with exception of PEO-IAA, AIB and nordihydroguaiaretic acid (NDGA) (Table 2)
Summary
Rice is one of the most important food crops worldwide, and an increased interest in developing high grain-yielding cultivars have led to the development of new varieties using conventional breeding programs [1]. Grain filling and Grain Yield (GY) are dependent on plant source/sink relationships, where the carbohydrates stored during pre-anthesis are mobilized from the vegetative tissues to the grains. Several genes associated with GY improvement have been identified by QTL analysis [2,3,4,5]. Most of the genes identified have been functionally associated with sink strengthening and only in the case of the gene THOUSANDGRAIN WEIGHT 6 (TGW6), a source reinforcement effect has been described [4]. PLOS ONE | DOI:10.1371/journal.pone.0131213 June 22, 2015
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