Não consigo atualização dos valores

Ola Boa tarde! Estou com um problema, criei duas classes cliente e endereço e relacionei elas com Hibernate (um-para-um), em endereço coloquei opção cascade=CascadeType.Persist . Agora estou querendo atualizar os valores sendo que me da um erro, não consigo resolver procurei em tudo, não encontrei nenhuma solução. podem me ajuda!

@RequestMapping("/form")
    public ModelAndView form(){
        ModelAndView modelAndView = new ModelAndView("cliente/clientes-form");
        //return "cliente/clientes-form";
        Endereco endereco = new Endereco();
        modelAndView.addObject("endereco", endereco);
        return modelAndView;
    }

    @RequestMapping( method=RequestMethod.POST)
    public String gravar(Cliente cliente,Endereco endereco){
        endereco.setCliente(cliente);
        enderecoDao.gravar(endereco);
        return "redirect:/clientes";
    }

    @RequestMapping(method=RequestMethod.GET)
    public ModelAndView listar(){
        List<Cliente> clientes = clienteDao.listar();
        ModelAndView modelAndView = new ModelAndView("cliente/listar-clientes");
        modelAndView.addObject("lista", clientes);
        return modelAndView;
    }

    @RequestMapping("/atualiza/{id}")
    public ModelAndView alteraCliente(@PathVariable("id")Integer id){
        ModelAndView modelAndView = new ModelAndView("cliente/atualiza-cliente");
        Cliente cliente = clienteDao.buscaId(id);
        modelAndView.addObject("cliente", cliente);
        Endereco endereco = enderecoDao.buscaId(cliente);
        modelAndView.addObject("endereco", endereco);
        return modelAndView;        

    }

    @RequestMapping("/atualiza-cliente")
    public ModelAndView atualizar(Cliente cliente,Endereco endereco){
        endereco.setCliente(cliente);
        enderecoDao.atualiza(endereco);
        return new ModelAndView("redirect:/clientes");
    }

Classe Cliente

@Entity
public class Cliente {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    @Column(length = 25, nullable = false)
    private String nome;

    @Column(length = 60, nullable = false)
    private String sobreNome;

    @Column(length = 60, nullable = false)
    private String razaoSocial;

    @Column(length = 60, nullable = false)
    private String nomeFantasia;

    @Column(length = 11 , nullable = false)
    private String cpf;

    @Column(length = 16 , nullable = false)
    private String cnpj;

    @Column(length = 30, nullable = false)
    private String tipoSistema;

    private int quantidade;

    @Column(length = 10 , nullable = false)
    private String telefone1;

    @Column(length = 10 , nullable = true)
    private String telefone2;

get e set...

Classe Endereço

@Entity
public class Endereco {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    @Column(length = 25, nullable = false)
    private String logradouro;

    @Column(length = 25, nullable = false)
    private String complemento;

    @Column(length = 25, nullable = false)
    private String bairro;

    @Column(length = 8, nullable = false)
    private String cep;

    @Column(length = 25, nullable =false)
    private String cidade;

    @OneToOne(optional=false, cascade =CascadeType.PERSIST)
    private Cliente cliente;

o erro é esse.

GRAVE: Servlet.service() for servlet [dispatcher] in context with path [/adnautomacao] threw exception [Request processing failed; nested exception is java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException: Not-null property references a transient value - transient instance must be saved before current operation : br.com.adnautomacao.modelos.Endereco.cliente -> br.com.adnautomacao.modelos.Cliente] with root cause
org.hibernate.TransientPropertyValueException: Not-null property references a transient value - transient instance must be saved before current operation : br.com.adnautomacao.modelos.Endereco.cliente -> br.com.adnautomacao.modelos.Cliente
    at org.hibernate.action.internal.UnresolvedEntityInsertActions.checkNoUnresolvedActionsAfterOperation(UnresolvedEntityInsertActions.java:137)
    at org.hibernate.engine.spi.ActionQueue.checkNoUnresolvedActionsAfterOperation(ActionQueue.java:314)
    at org.hibernate.internal.SessionImpl.checkNoUnresolvedActionsAfterOperation(SessionImpl.java:654)
    at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:874)
    at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:854)
    at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:859)
    at org.hibernate.jpa.spi.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:1196)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)