Expression of the Malus sieversii NF-YB21 Encoded Gene Confers Tolerance to Osmotic Stresses in Arabidopsis thaliana

Abstract

Drought is the main environmental factor that limits the yield and quality of apples (<i>Malus × domestica</i>) grown in arid and semi-arid regions. Nuclear factor Ys (NF-Ys) are important transcription factors involved in the regulation of plant growth, development, and various stress responses. However, the function of <i>NF-Y</i> genes is poorly understood in apples. Here, we identified 43 <i>NF-Y</i> genes in the genome of apples and conducted an initial functional characterization of the apple <i>NF-Y</i>. Expression analysis of <i>NF-Y</i> members in <i>M. sieversii</i> revealed that a large number of <i>NF-Ys</i> were highly expressed in the roots compared with the leaves, and a large proportion of <i>NF-Y</i> genes responded to drought treatment. Furthermore, heterologous expression of <i>MsNF-YB21,</i> which was significantly upregulated by drought, led to a longer root length and, thus, conferred improved osmotic and salt tolerance in <i>Arabidopsis</i>. Moreover, the physiological analysis of <i>MsNF-YB21</i> overexpression revealed enhanced antioxidant systems, including antioxidant enzymes and compatible solutes. In addition, genes encoding catalase (<i>AtCAT2</i>, <i>AtCAT3</i>), superoxide dismutase (<i>AtFSD1</i>, <i>AtFSD3</i>, <i>AtCSD1</i>), and peroxidase (<i>AtPER12</i>, <i>AtPER42</i>, <i>AtPER47</i>, <i>AtPER51</i>) showed upregulated expression in the <i>MsNF-YB21</i> overexpression lines. These results for the <i>MsNF-Y</i> gene family provide useful information for future studies on NF-Ys in apples, and the functional analysis of MsNF-YB21 supports it as a potential target in the improvement of apple drought tolerance via biotechnological strategies.