Fruit Development and Ripening

Abstract

Formation of fruits is a characteristic feature of angiosperms. Fruit types exhibit a great deal of diversity. They form an integral component of diet and provide not only vitamins and minerals but are also important source of antioxidants and fibers. Nutritional quality of the fruit is determined by various factors including those affecting the ripening stage. A fruit must have an optimum degree of ripeness so as to be consumed. Fruits are developed from less attractive immature stages to mature stages which attract seed-dispersing animals as well as human beings. Fruit ripening is a complex process, accomplished through several physiological, biochemical, and molecular mechanisms. These mechanisms also bring about changes in pigmentation due to loss of chlorophylls and a substantial increase in non-photosynthetic pigments, such as anthocyanins and carotenoids. Increase in the activity of cell wall hydrolases leads to fruit softening which is reflected in the texture of the mature fruit. Ripe fruits possess characteristic taste (due to elevated levels of sugars and depletion of organic acids) and aroma (due to biosynthesis of volatile compounds). Postharvest handling of the overripe fruits, however, is very difficult and adversely affects their storage and marketing.

Multiple-Choice Questions

• 1. A fruit is best defined as:

  • (a) Ripened ovule enclosing one or more seeds

  • (b) Ripened ovary enclosing one or more seeds

  • (c) Ripened endosperm enclosing one or more seeds

  • (d) Ripened nucellus enclosing one or more seeds

• 2. Which of the following statements is incorrect in the context of fruit development?

  • (a) Phase I is characterized by anthesis and successful fertilization.

  • (b) Phase II is characterized by rapid cell divisions during embryo development.

  • (c) Phase III is characterized by cessation of cell divisions and cell enlargement.

  • (d) Phase IV is characterized by enhanced carotenoid biosynthesis.

• 3. Which of the following is a non-climacteric fruit?

  • (a) Solanum lycopersicum

  • (b) Musa balbisiana

  • (c) Fragaria vesca

  • (d) Artocarpus heterophyllus

• 4. In climacteric fruits, exogenous application of ethylene results in:

  • (a) Autocatalytic induction of endogenous ethylene production if treated at pre-climacteric stage

  • (b) Autocatalytic induction of endogenous ethylene production if treated at mature climacteric fruit stage

  • (c) Increase in respiration rate

  • (d) Acceleration of fruit ripening

• 5. Which of the following statement is correct?

  • (a) Exogenous application of gibberellic acid (GA) leads to decrease in rate of respiration and degradation of chlorophyll.

  • (b) Exogenous application of auxin causes upregulation of polygalacturonase and expansin.

  • (c) Exogenous application of cytokinin enhances fruit ripening.

  • (d) Abscisic acid (ABA) is a positive regulator of fruit ripening.

• 6. Development of fruit without fertilization is called:

  • (a) Apospory

  • (b) Parthenogenesis

  • (c) Polygamy

  • (d) Parthenocarpy

Answers

1.b

2.a

3.c

4.a

5.b

6.d