Heat stress‐induced limitations to reproductive success in Gossypium hirsutum

Abstract

Using in vitro systems, numerous authors have cited the sensitivity of pollen tube growth to high temperature as a major cause of low yields for crops with valuable reproductive structures. We investigated the hypothesis that in vivo fertilization efficiency would be negatively affected by heat stress-induced changes in energy reserves and calcium-mediated oxidative status in the pistil. Gossypium hirsutum plants exposed to optimal (30/20 degrees C) or high day temperature (38/20 degrees C) conditions during flowering were analyzed for fertilization efficiency via UV microscopic observation of pollen tube-containing ovules and for soluble carbohydrates, adenosine triphosphate (ATP), calcium, antioxidant enzyme activity and NADPH oxidase (NOX; EC 1.6.3.1) activity in the pistil. Leaf measurements included gas exchange, chlorophyll content, quantum efficiency and ATP content of the subtending leaf on the day of anthesis. In the pistil fertilization efficiency, soluble carbohydrates, ATP content and NOX activity declined significantly, whereas water soluble calcium and glutathione reductase (EC 1.8.1.7) activity increased, and superoxide dismutase (EC 1.15.1.1) activity remained unchanged. In leaves, heat stress decreased photosynthesis, quantum efficiency and chlorophyll content, but increased stomatal conductance. We conclude that decreased source leaf activity either inhibits pollen development, tube growth through the style or guidance to the ovules as a result of an insufficient energy supply to the developing pistil. We further conclude that a calcium-augmented antioxidant response in heat-stressed pistils interferes with enzymatic superoxide production needed for normal pollen tube growth and fertilization of the ovule.

Shade Ameliorates High Temperature-induced Inhibition of Growth in Herbaceous Peony (Paeonia lactiflora)

“…4: Effect of shade treatment on the cell ultrastructure in P. lactiflora, A1: The mesophyll cell of P. lactiflora under Sun exposure in S1 (Bar=5um); A2: The mesophyll cell of P. lactiflora under shade treatment in S1 (Bar=5um); B1: The chloroplast of P. lactiflora under Sun exposure in S1 (Bar=0.5um); B2: The chloroplast of P. lactiflora under shade treatment in S1 (Bar=0.5um)；C1: The mesophyll cell of P. lactiflora under Sun exposure in S4 (Bar=5um); C2: The mesophyll cell of P. lactiflora under shade treatment in S4 (Bar=5um); D1: The chloroplast of P. lactiflora under Sun exposure (Bar=1um); D2: The chloroplast of P. lactiflora under shade treatment in S4 (Bar=1um) Note: CH = chloroplast, SG = starch grain, P = plastoglobuli, M = mitochondria Fig. 5: Nucleotide sequence and the deduced amino acid sequence of PlHSP70, the deduced amino acid sequence was showed underneath the corresponding nucleotide sequence, others was un-coding region, the deduced amino acid sequence with bold type and underline indicated three highly conserved HSP70 family signatures and stop code was indicated with *"Underlined amino acids were three highly conserved HSP70 family signatures Note: PlHSP60 = heat shock protein 60 gene in P. lactiflora, PlHSP70 = heat shock protein 70 gene in P. lactiflora, PlHSP90 = heat shock protein 90 gene in P. lactiflora, S1 = May, S2 = June, S3 = July, S4 = August growth of plants, resulting in a series of changes in plant morphology, anatomy, physiology, biochemistry and phenology drastically (Wahid et al, 2007;Snider et al, 2009). Therefore, it is important and urgent to take protective measures to reduce or alleviate the thermal damage of high temperature stress to plants.…”

Critical Roles of Vacuolar Invertase in Floral Organ Development and Male and Female Fertilities Are Revealed through Characterization of GhVIN1-RNAi Cotton Plants

“…For example, heat-stressed cotton plants also exhibit abnormal stigma protrusion, delayed anther dehiscence, and reduced pollen viability (Brown, 2001;Snider et al, 2009;Min et al, 2014) as well as high rates of boll shedding and seed abortion (Powell, 1969;Reddy et al, 1992;Brown, 2001). Min et al (2014) also reported that the impaired anther and pollen development under high temperature were associated with reduced expression of INV and starch synthesis genes, decreased Glc level, as well as disrupted auxin biosynthesis.…”

Relationship between Flower Opening in Six Cotton Cultivars and Their Progeny to Pollen Dehydration Tolerance

“…Cotton reproduction is strongly influenced by seasonal environmental conditions that determine yield potential and fiber quality [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Cotton flowers expand their petals the day before anthesis forming a shape commonly referred to as a "candle.…”