Distinct Preflowering Drought Tolerance Strategies of Sorghum bicolor Genotype RTx430 Revealed by Subcellular Protein Profiling.

Aaron J. Ogden,Kristin M. Engbrecht,Pubudu P. Handakumbura,Shadan Abdali,Mowei Zhou

doi:10.3390/ijms21249706

Abstract

Drought is the largest stress affecting agricultural crops, resulting in substantial reductions in yield. Plant adaptation to water stress is a complex trait involving changes in hormone signaling, physiology, and morphology. Sorghum (Sorghum bicolor (L.) Moench) is a C4 cereal grass; it is an agricultural staple, and it is particularly drought-tolerant. To better understand drought adaptation strategies, we compared the cytosolic- and organelle-enriched protein profiles of leaves from two Sorghum bicolor genotypes, RTx430 and BTx642, with differing preflowering drought tolerances after 8 weeks of growth under water limitation in the field. In agreement with previous findings, we observed significant drought-induced changes in the abundance of multiple heat shock proteins and dehydrins in both genotypes. Interestingly, our data suggest a larger genotype-specific drought response in protein profiles of organelles, while cytosolic responses are largely similar between genotypes. Organelle-enriched proteins whose abundance significantly changed exclusively in the preflowering drought-tolerant genotype RTx430 upon drought stress suggest multiple mechanisms of drought tolerance. These include an RTx430-specific change in proteins associated with ABA metabolism and signal transduction, Rubisco activation, reactive oxygen species scavenging, flowering time regulation, and epicuticular wax production. We discuss the current understanding of these processes in relation to drought tolerance and their potential implications.

Highlights

Drought is the primary abiotic factors negatively affecting agriculture [1], causing tremendous losses in yield worldwide [2,3]
To further understand RTx430 s unique drought tolerance, we report here a close examination of the protein-level drought response in organelle- and cytosolic-enriched cellular compartments (CCs)
Our analysis identified >3000 proteins in each CC that are enriched for proteins characteristic of each compartment, indicating a successful capture of organelle- and cytosolic-protein profiles

Summary

Introduction

Drought is the primary abiotic factors negatively affecting agriculture [1], causing tremendous losses in yield worldwide [2,3]. General adaptation strategies include accelerating the transition from vegetative to reproductive (escape), increasing internal water content (avoidance), and to continue growth with decreased internal water content (tolerance) [5]. Each of these adaptation strategies require complex molecular responses to drought, including hormone signaling [6] and production of osmoprotectants [7], as well as developmental responses including stomatal closure, changes to leaf morphology, and altered root system architecture [8]. A common strategy to better understand these adaptation mechanisms is to compare plants with differing drought tolerances; this has been successful in multiple crop plants including wheat, rice, maize, and sorghum [9]

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