ZmMs30 Encoding a Novel GDSL Lipase Is Essential for Male Fertility and Valuable for Hybrid Breeding in Maize

Abstract

Genic male sterility (GMS) is very useful for hybrid vigor utilization and hybrid seed production. Although a large number of GMS genes have been identified in plants, little is known about the roles of GDSL lipase members in anther and pollen development. Here, we report a maize GMS gene, ZmMs30, which encodes a novel type of GDSL lipase with diverged catalytic residues. Enzyme kinetics and activity assays show that ZmMs30 has lipase activity and prefers to substrates with a short carbon chain. ZmMs30 is specifically expressed in maize anthers during stages 7-9. Loss of ZmMs30 function resulted in defective anther cuticle, irregular foot layer of pollen exine, and complete male sterility. Cytological and lipidomics analyses demonstrate that ZmMs30 is crucial for the aliphatic metabolic pathway required for pollen exine formation and anther cuticle development. Furthermore, we found that male sterility caused by loss of ZmMs30 function was stable in various inbred lines with different genetic background, and that it didn't show any negative effect on maize heterosis and production, suggesting that ZmMs30 is valuable for cross-breeding and hybrid seed production. We then developed a new multi-control sterility system using ZmMs30 and its mutant line, and demonstrated it is feasible for generating desirable GMS lines and valuable for hybrid maize seed production. Taken together, our study sheds new light on the mechanisms of anther and pollen development, and provides a valuable male-sterility system for hybrid breeding maize.

Keywords: GDSL lipase; ZmMs30; hybrid seed production; maize; multi-control sterility (MCS) system.